Anomaly calculation

[Boyin Huang]

I have observed temperature OT (file1) from 1982 to 2000.
I have simulated temperature ST (file2) from 1981 to 2000.

I want to calculate anomaly=ST-OT from 1982 to 2000.

the following script works, but not sure it is right or not:

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open file1
set t 1 19
define v1=OT

open file2
set t 1 20 (should I use "set t 2 20" to match the time?)
define v2=ST.2

d v2-v1
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